CXCL8-mediated glial cross-talk and neuroprotection in HIV-1 Dementia

描述（由申请人提供）：目前，全球约有3500万人感染HIV-1。HIV-1相关痴呆（HAD）与轻度神经认知障碍和无症状神经认知障碍一起构成HIV相关神经认知障碍（HAND）。与轻度形式的HIV脑炎相关的炎症显示炎症区域存在活化的小胶质细胞，反应性星形胶质细胞增生和神经元损伤。几年前，我们开始对神经胶质细胞激活的潜在机制及其在神经艾滋病中的作用进行新的研究。在初步实验中使用的是人神经胶质细胞，CXCL8是激活的星形胶质细胞和其他神经细胞中上调的关键分子之一。重要的是，CXCL8在暴露于hiv -1相关神经毒素的培养人类神经元中具有神经保护作用。与年龄匹配的对照组相比，hiv -1感染的脑组织显示出更高的CXCL8水平，进一步证实了这一观察结果的生物学相关性。我们认为CXCL8在HIV-1中枢神经系统感染的细胞间相互作用中起着关键的调节作用。小胶质细胞感染和激活导致IL-12的上调。IL-12是星形胶质细胞的一种典型炎症刺激，可促进中枢神经系统星形胶质细胞产生CXCL8。CXCL8进一步募集小胶质细胞并调节小胶质细胞活化和HIV-1感染。综上所述，这些事件最终可能导致cxcl8介导的直接或间接神经保护。为此，我们将解决以下具体问题：在HAD中活化的星形胶质细胞中CXCL8是如何调节的，涉及什么机制？（目的1）胶质细胞CXCL8如何调节小胶质细胞募集、激活和感染？（目的2）在HAD过程中，CXCL8如何调节神经元的存活和/或功能？（目标3）在目标1中，将利用人脑组织标本和原代人神经细胞来描绘CXCL8的谱，并确定HAD中CXCL8的细胞来源。原代人神经细胞将暴露于had特异性刺激和CXCL8调节将被评估。星形胶质细胞中参与IL-8调节的细胞内信号通路，特别是NF-:B， p38MAPK和/或SHP2将被研究。激活的星形胶质细胞和小胶质细胞之间通过cxcl8介导的细胞间相互作用在小胶质细胞激活、募集和HIV-1感染的调节中的作用将在Aim 2中进行评估。CXCL8的神经保护机制和随后的信号转导，特别是通过Akt/PKB， ERK1/2， Bcl-2和Bax，以及TNF受体在这些神经保护事件中的作用将在Aim 3中使用人原代神经元进行研究。综上所述，本研究将提供关于cxcl8介导的胶质细胞串话和神经发病机制的新数据，并对胶质细胞炎症反应的调节提供新的见解，具有基础和临床意义。公共卫生相关性：迄今为止，全世界有近6 000万人感染了人体免疫缺陷病毒-1。hiv相关神经认知障碍（HAND）由HIV-1相关痴呆（HAD）和其他神经认知障碍组成，是HIV-1感染的重要神经系统并发症。在美国等发达国家，尽管抗逆转录病毒治疗非常有效，但估计仍有10-15%的HIV血清阳性（HIV+）患者进展为HAD。神经胶质炎症是这种疾病的一个重要机制，该提案的数据将更好地理解激活的神经胶质对hiv -1痴呆的具体机制贡献，并对神经保护具有更广泛的意义。

DESCRIPTION (provided by applicant): Currently, almost 35 million people live with HIV-1 infection worldwide. HIV-1-associated dementia (HAD) along with mild neurocognitive disorder and asymptomatic neurocognitive impairment comprises the HIV- associated neurocognitive disorder (HAND). Inflammation associated with milder forms of HIV encephalitis shows presence of activated microglia, reactive astrogliosis and neuronal injury in areas of inflammation. A few years ago, we began novel investigations into the potential mechanisms associated with glial activation & their contribution in neuro-AIDS. Primary human glial cells were used in preliminary experiments and CXCL8 was among the key molecules upregulated in activated astrocytes and other neural cells. Importantly, CXCL8 was neuroprotective in cultured human neurons exposed to HIV-1-related neurotoxins. Biological relevance of this observation was further confirmed as HIV-1-infected brain tissues demonstrated greater CXCL8 levels as compared to age-matched controls. We propose that CXCL8 plays a key regulatory role in the intercellular interactions in HIV-1 CNS infection. Microglial infection and activation leads to upregulation of IL-12. IL-12, a prototypical inflammatory stimulus for astrocytes, enhances CXCL8 production by astrocytes in CNS. CXCL8 further recruits microglia and regulates microglial activation and HIV-1 infection. Taken together, ultimately these events may lead to CXCL8-mediated direct or indirect neuroprotection. To these ends, we will address the following specific questions: How is CXCL8 regulated in activated astrocytes in HAD and what mechanisms are involved? (Aim 1) How does glial CXCL8 regulate microglial recruitment, activation and infection? (Aim 2) How does CXCL8 regulate neuronal survival and/or function during the process of HAD? (Aim 3) In Aim 1, human brain tissue specimens and primary human neural cells will be utilized to delineate CXCL8 profiles and to identify the cellular sources for CXCL8 in HAD. Primary human neural cells will be exposed to HAD-specific stimuli and CXCL8 regulation will be evaluated. The intracellular signaling pathways involved in IL-8 regulation, specifically, NF-:B, p38MAPK and/or SHP2 will be studied in astrocytes. The role of intercellular interactions between activated astrocytes and microglia via CXCL8-mediated in regulation of microglial activation, recruitment and HIV-1 infection will be evaluated in Aim 2. The mechanisms of CXCL8 neuroprotection and the ensuing signal transduction specifically through Akt/PKB, ERK1/2, Bcl-2 and Bax and the role of TNF receptors in these neuroprotective events will be investigated using primary human neurons in Aim 3. Taken together, the studies proposed in this application will provide novel data about CXCL8-mediated glial cross-talk and neuropathogenesis and lead to novel insights into regulation of glial inflammatory responses that have both basic and clinical significance. PUBLIC HEALTH RELEVANCE: To date, almost 60 million people have been infected worldwide with the human immunodeficiency virus -1. HIV-associated neurocognitive disorder (HAND) that consists of HIV-1-associated dementia (HAD) along with other neurocognitive impairments, is an important neurological complication of HIV-1 infection. An estimated 10-15% of HIV-seropositive (HIV+) patients progress to HAD in developed worlds such as the United States, despite highly active antiretroviral therapy. Glial inflammation is an important mechanism involved in this disease and the data from this proposal will provide a better understanding of the specific mechanistic contributions of activated glia to HIV-1-dementia and have broader implications for neuroprotection.